Effects of Barrier Energy Offset and Gradient in Extended Wavelength Infrared Detectors

The extended wavelength infrared (IR) photodetectors are the new class of III-V semiconductor heterojunction-based photodetectors that can detect incoming radiation with energy significantly smaller than the minimum energy gap (
Δ
) at the heterojunction interface. The architecture of these photodetectors includes a barrier-emitter-barrier epilayers sandwiched between highly doped ohmic top and bottom contact layers. An energy offset
$(\delta E)$
between the barriers is necessary for the extended wavelength photodetection. In this article, we study the performance of extended wavelength IR photodetectors with varying
$\delta E$
and gradient of the potential barrier. Results indicate that the extended wavelength threshold varied slightly with varying both the gradient and offset. Spectral responsivity, however, increased with the increasing offset and decreased with increasing gradient.